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<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"><meta name="description" content="记录生活"><meta name="keywords" content=""><meta name="author" content="浩然天成"><meta name="copyright" content="浩然天成"><title>Aron | Aron</title><link rel="shortcut icon" href="/melody-favicon.ico"><link rel="stylesheet" href="/css/index.css?version=1.9.0"><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/font-awesome@latest/css/font-awesome.min.css?version=1.9.0"><meta name="format-detection" content="telephone=no"><meta http-equiv="x-dns-prefetch-control" content="on"><link rel="dns-prefetch" href="https://cdn.jsdelivr.net"><meta http-equiv="Cache-Control" content="no-transform"><meta http-equiv="Cache-Control" content="no-siteapp"><script>var GLOBAL_CONFIG = { 
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<li><p>自动生成<code>target</code>文件夹存放可执行文件。</p>
</li>
<li><p>自动生成<code>obj</code>文件夹存放编译生成的目标文件<code>.o</code></p>
</li>
<li><p>支持调试版本的编译选项</p>
</li>
<li><p>考虑代码的扩展性</p>
</li>
<li><p><code>$(wildcard _pattern)</code></p>
<p> 满足_pattern的文件或目录列表</p>
</li>
<li><p><code>$(addprefix _prefix,names)</code></p>
<p> 给名字列表names中的每一个名字曾家前缀_prefix.</p>
</li>
</ol>
<h2 id="Skill"><a href="#Skill" class="headerlink" title="Skill"></a>Skill</h2><ol>
<li>自动获取当前目录下的源文件列表（函数调用）</li>
</ol>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">SRCS := <span class="variable">$(<span class="built_in">wildcard</span> *.c)</span></span><br></pre></td></tr></table></figure>

<ol>
<li>根据源文件列表生成目标文件列表（变量的值替换）</li>
</ol>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">OBJS := $(SRCS:.c =.o)</span><br><span class="line"><span class="comment">#不能有空格</span></span><br></pre></td></tr></table></figure>

<ol>
<li>对每一个目标文件列表加上路径前缀（函数调用）</li>
</ol>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">OBJS := ( addprefix path/ , <span class="variable">$(OBJS)</span> )</span><br></pre></td></tr></table></figure>

<h3 id="规则中的模式替换"><a href="#规则中的模式替换" class="headerlink" title="规则中的模式替换"></a>规则中的模式替换</h3><figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">%.o : %.c</span><br><span class="line">	gcc -o <span class="variable">$@</span> -c <span class="variable">$^</span></span><br></pre></td></tr></table></figure>

<p>针对于当前工作目录</p>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">OBJS := func.o main.o</span><br><span class="line"><span class="variable">$(OBJS)</span> : %.c</span><br><span class="line">	gcc -o <span class="variable">$@</span> -c <span class="variable">$^</span></span><br></pre></td></tr></table></figure>

<p>针对于变量（OBJS）列表</p>
<h3 id="编译规则中的依赖"><a href="#编译规则中的依赖" class="headerlink" title="编译规则中的依赖"></a>编译规则中的依赖</h3><figure class="highlight properties"><table><tr><td class="code"><pre><span class="line">				<span class="meta">-&gt;dirs</span>           <span class="string">(创建文件夹)</span></span><br><span class="line"><span class="attr">all</span> <span class="string">-&gt; targets -&gt; -&gt;objs           (生成可执行文件)</span></span><br><span class="line">				<span class="meta">-&gt;生成可执行文件</span>   <span class="string">（链接）</span></span><br></pre></td></tr></table></figure>


<h2 id="Summary"><a href="#Summary" class="headerlink" title="Summary"></a>Summary</h2><ul>
<li>目录可以成为目标的依赖，在规则中创建目录。</li>
<li>预定义函数是makefile实战中时不可或缺的部分。</li>
<li>规则中的模式匹配可以直接针对目录中的文件。</li>
<li>可以使用命令行变量便须特殊的目标版本。</li>
</ul>
<h2 id="工程实例"><a href="#工程实例" class="headerlink" title="工程实例"></a>工程实例</h2><p>在工程文件夹下新建立了<code>main.c</code> <code>func.c</code> <code>func.h</code>.（放在同一文件夹下）。</p>
<p>现在已经是第二天。如果<code>.H</code> 文件放在<code>inc</code>文件夹下面会更合适。也会更加符合实际的工程应用。</p>
<h3 id="main-c"><a href="#main-c" class="headerlink" title="main.c"></a><code>main.c</code></h3><figure class="highlight c"><table><tr><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">include</span> <span class="meta-string">&quot;func.h&quot;</span></span></span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">int</span> <span class="title">main</span><span class="params">()</span></span>&#123;</span><br><span class="line">    print(<span class="string">&quot;%s\n&quot;</span>,);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h3 id="func-c"><a href="#func-c" class="headerlink" title="func.c"></a><code>func.c</code></h3><figure class="highlight c"><table><tr><td class="code"><pre><span class="line"><span class="keyword">const</span> <span class="keyword">char</span>* String = <span class="string">&quot;My Densitiy&quot;</span></span><br></pre></td></tr></table></figure>

<h3 id="func-h"><a href="#func-h" class="headerlink" title="func.h"></a><code>func.h</code></h3><figure class="highlight c"><table><tr><td class="code"><pre><span class="line"><span class="meta">#<span class="meta-keyword">ifndef</span> __FUNC__</span></span><br><span class="line"><span class="meta">#<span class="meta-keyword">define</span> __FUNC__</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">extern</span> cont <span class="keyword">char</span>* String;</span><br><span class="line"><span class="meta">#<span class="meta-keyword">endif</span></span></span><br></pre></td></tr></table></figure>

<h3 id="makefile"><a href="#makefile" class="headerlink" title="makefile"></a>makefile</h3><figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">CC := gcc</span><br><span class="line">MKDIR := mkdir</span><br><span class="line">RM := rm -fr</span><br><span class="line"></span><br><span class="line">DIR_OBJS := objs</span><br><span class="line">DIR_TARGET := target</span><br><span class="line"></span><br><span class="line">DIRS := <span class="variable">$(DIR_OBJS)</span> <span class="variable">$(DIR_TARGET)</span></span><br><span class="line"></span><br><span class="line">TARGET := <span class="variable">$(DIR_TARGET)</span>/hello_makefile.out</span><br><span class="line"></span><br><span class="line">SRCS := <span class="variable">$(<span class="built_in">wildcard</span> *.c)</span></span><br><span class="line"><span class="comment">#获取源文件列表</span></span><br><span class="line"><span class="comment">#main.c func.c</span></span><br><span class="line"></span><br><span class="line">OBJS := $(SRCS:.c=.o)   </span><br><span class="line"><span class="comment">#值替换 main.o func.o</span></span><br><span class="line"><span class="comment">#debug <span class="doctag">TODO:</span>can&#x27;t use to space in $(SRCS:.c=.o)</span></span><br><span class="line"><span class="comment">#用于生成目录下的列表</span></span><br><span class="line"></span><br><span class="line">OBJS := <span class="variable">$(<span class="built_in">addprefix</span> <span class="variable">$(DIR_OBJS)</span>/, <span class="variable">$(OBJS)</span>)</span> </span><br><span class="line"><span class="comment">#添加路径前缀objs/main.o</span></span><br><span class="line"><span class="comment">#objs/mian.o objs/func.o</span></span><br><span class="line"></span><br><span class="line"><span class="meta"><span class="meta-keyword">.PHONY</span>: rebuild clean all</span></span><br><span class="line"></span><br><span class="line"><span class="variable">$(TARGET)</span> : <span class="variable">$(DIRS)</span> <span class="variable">$(OBJS)</span></span><br><span class="line">	@<span class="variable">$(CC)</span> -o <span class="variable">$@</span> <span class="variable">$(OBJS)</span></span><br><span class="line">	@echo <span class="string">&quot;Target File ==&gt; <span class="variable">$@</span>&quot;</span></span><br><span class="line">	@./<span class="variable">$(TARGET)</span></span><br><span class="line">	</span><br><span class="line"><span class="variable">$(DIRS)</span>:</span><br><span class="line">	@<span class="variable">$(MKDIR)</span> <span class="variable">$@</span></span><br><span class="line"></span><br><span class="line"><span class="variable">$(DIR_OBJS)</span>/%.o : %.c</span><br><span class="line">    <span class="keyword">ifeq</span> (<span class="variable">$(DEBUG)</span>,true)</span><br><span class="line">		@<span class="variable">$(CC)</span> -o <span class="variable">$@</span> -g -c <span class="variable">$^</span></span><br><span class="line">    <span class="keyword">else</span></span><br><span class="line">		@<span class="variable">$(CC)</span> -o <span class="variable">$@</span> -c <span class="variable">$^</span></span><br><span class="line">    <span class="keyword">endif</span></span><br><span class="line"></span><br><span class="line"><span class="section">rebuild:clean all</span></span><br><span class="line"></span><br><span class="line">all : <span class="variable">$(TARGET)</span></span><br><span class="line"></span><br><span class="line"><span class="section">clean:</span></span><br><span class="line">	<span class="variable">$(RM)</span> <span class="variable">$(DIRS)</span></span><br></pre></td></tr></table></figure></div><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2021/04/11/%E2%85%A4%E9%A2%84%E5%AE%9A%E4%B9%89%E5%8F%98%E9%87%8F%E7%9A%84%E4%BD%BF%E7%94%A8/">Ⅴ预定义变量的使用</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2021-04-11</time><span class="article-meta tags"><span class="article-meta__separator">|</span><i class="fa fa-tag article-meta__icon" aria-hidden="true"></i><a class="article-meta__tags" href="/tags/makefile/">makefile</a></span><div class="content"><a id="more"></a>预定义变量中存在两类变量，一类是自动变量，一类是特殊变量<!--more-->
<ul>
<li>自动变量</li>
</ul>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="meta">$@</span> <span class="string">$^ $&lt;</span></span><br></pre></td></tr></table></figure>

<ul>
<li>特殊变量</li>
</ul>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">$(MAKE),$(MAKECMDGOALS),$(MAKEFILE_LIST)</span></span><br><span class="line"><span class="attr">$(MAKE_VERSION),$(CURDIR),$(VARIABLES)</span></span><br><span class="line"><span class="attr">etc...</span></span><br></pre></td></tr></table></figure>

<h2 id="自动变量的意义"><a href="#自动变量的意义" class="headerlink" title="自动变量的意义"></a>自动变量的意义</h2><h3 id=""><a href="#" class="headerlink" title="$@"></a>$@</h3><pre><code>当前规则中触发命令被执行的目标</code></pre>
<h3 id="-1"><a href="#-1" class="headerlink" title="$^"></a>$^</h3><pre><code>当前规则中的所有依赖</code></pre>
<h3 id="lt"><a href="#lt" class="headerlink" title="$&lt;"></a>$&lt;</h3><pre><code>当前规则中的第一个依赖</code></pre>
<h3 id="自动变量的使用示例"><a href="#自动变量的使用示例" class="headerlink" title="自动变量的使用示例"></a>自动变量的使用示例</h3><figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">hello : main.o func.o</span><br><span class="line">	gcc -o <span class="variable">$@</span> <span class="variable">$^</span></span><br><span class="line"></span><br><span class="line">%.o : %.c</span><br><span class="line">	gcc -o <span class="variable">$@</span> -c <span class="variable">$&lt;</span></span><br></pre></td></tr></table></figure>


<h2 id="一些特殊变量的意义"><a href="#一些特殊变量的意义" class="headerlink" title="一些特殊变量的意义"></a>一些特殊变量的意义</h2><h3 id="MAKE"><a href="#MAKE" class="headerlink" title="$(MAKE)"></a>$(MAKE)</h3><pre><code>当前make解释器的文件名</code></pre>
<h3 id="MAKECMDGOALS"><a href="#MAKECMDGOALS" class="headerlink" title="$(MAKECMDGOALS)"></a>$(MAKECMDGOALS)</h3><pre><code>命令行中指定的目标名(make的命令行参数)</code></pre>
<h3 id="MAKEFILE-LIST"><a href="#MAKEFILE-LIST" class="headerlink" title="$(MAKEFILE_LIST)"></a>$(MAKEFILE_LIST)</h3><pre><code>make所需要的处理的makefile文件列表

当前makefile的文件名总是位于列表的最后

文件名之间以空格进行分割</code></pre>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line"><span class="meta"><span class="meta-keyword">.PHONY</span>: all out first second third unload</span></span><br><span class="line"></span><br><span class="line">all out:</span><br><span class="line">	@echo <span class="string">&quot;\$<span class="variable">$(MAKE)</span>=&gt; <span class="variable">$(MAKE)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;\$$MAKECMDGOALS=&gt; <span class="variable">$(MAKECMDGOALS)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;\$<span class="variable">$(MAKEFILE_LIST)</span>=&gt; <span class="variable">$(MAKEFILE_LIST)</span>&quot;</span></span><br><span class="line"></span><br><span class="line"><span class="section">first:</span></span><br><span class="line">	@echo <span class="string">&quot;\$$MAKECMDGOALS=&gt; <span class="variable">$(MAKECMDGOALS)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;first&quot;</span></span><br><span class="line"><span class="section">second:</span></span><br><span class="line">	@echo <span class="string">&quot;\$$MAKECMDGOALS=&gt; <span class="variable">$(MAKECMDGOALS)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;second&quot;</span></span><br><span class="line"><span class="section">third:</span></span><br><span class="line">	@echo <span class="string">&quot;\$$MAKECMDGOALS=&gt; <span class="variable">$(MAKECMDGOALS)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;third&quot;</span></span><br><span class="line">	</span><br><span class="line"><span class="section">test:</span></span><br><span class="line">	@<span class="variable">$(MAKE)</span> first</span><br><span class="line">	@<span class="variable">$(MAKE)</span> second</span><br><span class="line">	@<span class="variable">$(MAKE)</span> third</span><br><span class="line">	<span class="comment">##文末这种调用方式，适用于大型工程多个makefile的调用##</span></span><br><span class="line">	<span class="comment">##但不能实现多文件的调用##</span></span><br></pre></td></tr></table></figure>

<p><img src="C:\Users\aron\Desktop\blog\source_posts\Ⅴ预定义变量的使用\image-20210411175744920.png" alt="image-20210411175744920"></p>
<h3 id="MAKE-VERSION"><a href="#MAKE-VERSION" class="headerlink" title="$(MAKE_VERSION)"></a>$(MAKE_VERSION)</h3><pre><code>当前make解释器的版本</code></pre>
<h3 id="CURDIR"><a href="#CURDIR" class="headerlink" title="$(CURDIR)"></a>$(CURDIR)</h3><pre><code>当前make解释器的工作目录</code></pre>
<h3 id="VARIABLES"><a href="#VARIABLES" class="headerlink" title="$(.VARIABLES)"></a>$(.VARIABLES)</h3><pre><code>所有已经定义的变量名列表（预定义变量和自定义变量）</code></pre>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line"><span class="meta"><span class="meta-keyword">.PHONY</span>: test1 test2</span></span><br><span class="line"></span><br><span class="line">ZHC := Aron</span><br><span class="line"><span class="section">test1:</span></span><br><span class="line">	@echo <span class="string">&quot;\$<span class="variable">$(MAKE_VERSION)</span> =&gt; <span class="variable">$(MAKE_VERSION)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;\$<span class="variable">$(CURDIR)</span> =&gt; <span class="variable">$(CURDIR)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;\$$(。VARIABLES) =&gt; $(.VARIABLES)&quot;</span></span><br><span class="line">	</span><br><span class="line"><span class="comment">##我们可以通过(.VARIABLES)去查看该版本下的预定义的特殊变量，具体的解释需要到gnu官网去查看##</span></span><br></pre></td></tr></table></figure>

<p><img src="C:\Users\aron\Desktop\blog\source_posts\Ⅴ预定义变量的使用\image-20210411175525011.png" alt="image-20210411175525011"></p>
<h2 id="小结"><a href="#小结" class="headerlink" title="小结"></a>小结</h2><p>makefile提供了预定义变量供开发者使用</p>
<p>预定义变量的使用能够使得 makefile的开发更高效</p>
<p>自动变量是makefile中最常见的元素</p>
<p>使用$(.VARIABLES)能够获取所有的特殊变量</p>
<hr>
<h2 id="小问题"><a href="#小问题" class="headerlink" title="小问题"></a>小问题</h2><p>makefile中能否实现 类似C语言 中多文件调用的情况?</p>
</div><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2021/04/09/%E2%85%A3%E5%8F%98%E9%87%8F%E5%92%8C%E4%B8%8D%E5%90%8C%E7%9A%84%E8%B5%8B%E5%80%BC%E6%96%B9%E5%BC%8F/">Ⅳ变量和不同的赋值方式</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2021-04-09</time><span class="article-meta tags"><span class="article-meta__separator">|</span><i class="fa fa-tag article-meta__icon" aria-hidden="true"></i><a class="article-meta__tags" href="/tags/makefile/">makefile</a></span><div class="content"><a id="more"></a>
<ul>
<li><p>makefile中支持程序设计语言中<code>变量的概念</code></p>
</li>
<li><p>makefile中的变量<code>只代表文本数据</code>( 字符串 )</p>
</li>
<li><p>makefile中的变量名规则<!--more--></p>
</li>
</ul>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">-变量名可以包含字符,数字,下划线.</span></span><br><span class="line"><span class="meta">-不能包含&quot;</span>:<span class="string">&quot; , &quot;#&quot; ,&quot;=&quot; 或 &quot; &quot;</span></span><br><span class="line"><span class="attr">-变量名大小写敏感</span></span><br></pre></td></tr></table></figure>


<h2 id="变量的定义和使用"><a href="#变量的定义和使用" class="headerlink" title="变量的定义和使用"></a>变量的定义和使用</h2><figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">CC := gcc</span><br><span class="line">TARGET := hello.out</span><br><span class="line"></span><br><span class="line"><span class="variable">$(TARGET)</span> : func.o main.o</span><br><span class="line">	<span class="variable">$(CC)</span> -o <span class="variable">$(TARGET)</span> fun.o main.o</span><br><span class="line">	</span><br><span class="line"><span class="comment">##开始的两行表示 变量的定义##</span></span><br><span class="line"><span class="comment">##使用的时候 需要加上 $() ,变量名填入其中##</span></span><br></pre></td></tr></table></figure>

<h3 id="makefile中变量的赋值方式"><a href="#makefile中变量的赋值方式" class="headerlink" title="makefile中变量的赋值方式"></a>makefile中变量的赋值方式</h3><figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="meta">-简单赋值</span> <span class="string">( := )</span></span><br><span class="line"><span class="meta">-递归赋值</span> <span class="string">( =  )</span></span><br><span class="line"><span class="meta">-条件赋值</span> <span class="string">( ?= )</span></span><br><span class="line"><span class="meta">-追加赋值</span> <span class="string">( += )</span></span><br></pre></td></tr></table></figure>

<h4 id="简单赋值"><a href="#简单赋值" class="headerlink" title="简单赋值( := )"></a>简单赋值( := )</h4><ul>
<li>程序设计语言中的通用的赋值方法</li>
<li>只针对当前语句的变量有效</li>
</ul>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">x := foo</span><br><span class="line">y := <span class="variable">$(x)</span>b</span><br><span class="line">x := new</span><br><span class="line"></span><br><span class="line"><span class="meta"><span class="meta-keyword">.PHONY</span>: test</span></span><br><span class="line"><span class="section">test:</span></span><br><span class="line">	@echo <span class="string">&quot;x=&gt; <span class="variable">$(x)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;y=&gt; <span class="variable">$(y)</span>&quot;</span></span><br></pre></td></tr></table></figure>

<p>输出结果:</p>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">x</span>=<span class="string">&gt; foo</span></span><br><span class="line"><span class="attr">y</span>=<span class="string">&gt; foob</span></span><br></pre></td></tr></table></figure>


<h4 id="递归赋值"><a href="#递归赋值" class="headerlink" title="递归赋值( = )"></a>递归赋值( = )</h4><ul>
<li>赋值操作可能影响多个其他变量.</li>
<li>所有与目标变量相关的其他变量都将受到其影响.</li>
</ul>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">x := foo</span><br><span class="line">y := <span class="variable">$(x)</span>b</span><br><span class="line">x = new</span><br><span class="line"></span><br><span class="line">.PHONY : test</span><br><span class="line"><span class="section">test:</span></span><br><span class="line">	@echo <span class="string">&quot;x=&gt; <span class="variable">$(x)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;y=&gt; <span class="variable">$(y)</span>&quot;</span></span><br></pre></td></tr></table></figure>

<p>输出结果:</p>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">x</span>=<span class="string">&gt; new</span></span><br><span class="line"><span class="attr">y</span>=<span class="string">&gt; newb</span></span><br></pre></td></tr></table></figure>


<h4 id="条件赋值"><a href="#条件赋值" class="headerlink" title="条件赋值( ?= )"></a>条件赋值( ?= )</h4><ul>
<li>如果变量未定义,使用赋值符号中的值定义变量</li>
<li>如果变量已经定义,赋值无效</li>
</ul>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">x := foo</span><br><span class="line">y := <span class="variable">$(x)</span>b</span><br><span class="line">x ?= new</span><br><span class="line">c ?= WHL</span><br><span class="line"></span><br><span class="line">.PHONY : test</span><br><span class="line"><span class="section">test:</span></span><br><span class="line">	@echo <span class="string">&quot;x=&gt; <span class="variable">$(x)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;y=&gt; <span class="variable">$(y)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;c=&gt; <span class="variable">$(c)</span>&quot;</span></span><br></pre></td></tr></table></figure>

<p>输出结果:</p>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">x</span>=<span class="string">&gt; foo</span></span><br><span class="line"><span class="attr">y</span>=<span class="string">&gt; foob</span></span><br><span class="line"><span class="attr">c</span>=<span class="string">&gt; WHL</span></span><br></pre></td></tr></table></figure>


<h4 id="追加赋值"><a href="#追加赋值" class="headerlink" title="追加赋值( += )"></a>追加赋值( += )</h4><ul>
<li>原变量之后加上一个新值</li>
<li>原变量值与新值之间有空格隔开</li>
</ul>
<figure class="highlight makefile"><table><tr><td class="code"><pre><span class="line">x := foo</span><br><span class="line">y := <span class="variable">$(x)</span>b</span><br><span class="line">x += y</span><br><span class="line"></span><br><span class="line">.PHONY : test</span><br><span class="line"><span class="section">test:</span></span><br><span class="line">	@echo <span class="string">&quot;x=&gt; <span class="variable">$(x)</span>&quot;</span></span><br><span class="line">	@echo <span class="string">&quot;y=&gt; <span class="variable">$(y)</span>&quot;</span></span><br></pre></td></tr></table></figure>

<p>输出结果:</p>
<figure class="highlight properties"><table><tr><td class="code"><pre><span class="line"><span class="attr">x</span>=<span class="string">&gt; foo foob</span></span><br><span class="line"><span class="attr">y</span>=<span class="string">&gt; foob</span></span><br></pre></td></tr></table></figure>

</div><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2021/04/09/%E6%9E%84%E9%80%A0%E5%87%BD%E6%95%B0/">构造函数</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2021-04-09</time><span class="article-meta tags"><span class="article-meta__separator">|</span><i class="fa fa-tag article-meta__icon" aria-hidden="true"></i><a class="article-meta__tags" href="/tags/C/">C++</a></span><div class="content"><a id="more"></a><!--more--></div><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2021/03/05/ControlTheory_%E2%85%A0/">ControlTheory Ⅰ</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2021-03-05</time><div class="content"></div><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2020/10/31/C8051F380%E5%88%9D%E7%BA%A7%E6%95%99%E7%A8%8B-1/">C8051F380初级教程(1)</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2020-10-31</time><span class="article-meta tags"><span class="article-meta__separator">|</span><i class="fa fa-tag article-meta__icon" aria-hidden="true"></i><a class="article-meta__tags" href="/tags/%E5%8D%95%E7%89%87%E6%9C%BA-%EF%BC%8C%E6%95%99%E7%A8%8B/">单片机 ，教程</a></span><div class="content"><p>​        首先说说我做这个的目的，首先是为了整理知识，另外为了分享出来，让自己实现一些个人价值。</p>
<p>​        另外这个教程会写多久？预计在2021年6月1日写完。目前制作这个教程的计划，还没有明确规划，但是先划一个<code>Death Line</code></p></div><a class="more" href="/2020/10/31/C8051F380%E5%88%9D%E7%BA%A7%E6%95%99%E7%A8%8B-1/#more">Read more</a><hr></div><div class="recent-post-item article-container"><a class="article-title" href="/2020/10/23/%E8%87%AA%E6%88%91%E4%BB%8B%E7%BB%8D/">自我介绍</a><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2020-10-23</time><span class="article-meta tags"><span class="article-meta__separator">|</span><i class="fa fa-tag article-meta__icon" aria-hidden="true"></i><a class="article-meta__tags" href="/tags/%E4%BB%8B%E7%BB%8D/">介绍</a></span><div class="content"><p>欢迎来到<code>Aron Blog</code>，这是第一次自己成功搭建的博客，是我很喜欢的蓝色。欢迎大家提出意见。</div><a class="more" href="/2020/10/23/%E8%87%AA%E6%88%91%E4%BB%8B%E7%BB%8D/#more">Read more</a><hr></div><nav id="pagination"><div class="pagination"><span class="page-number current">1</span></div></nav></div></div><footer><div class="layout" id="footer"><div class="copyright">&copy;2013 - 2021 By 浩然天成</div><div class="framework-info"><span>Driven - </span><a target="_blank" rel="noopener" href="http://hexo.io"><span>Hexo</span></a><span class="footer-separator">|</span><span>Theme - </span><a target="_blank" rel="noopener" href="https://github.com/Molunerfinn/hexo-theme-melody"><span>Melody</span></a></div><div class="busuanzi"><script async src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js"></script><span id="busuanzi_container_site_uv"><i class="fa fa-user"></i><span id="busuanzi_value_site_uv"></span><span></span></span><span class="footer-separator">|</span><span id="busuanzi_container_site_pv"><i class="fa fa-eye"></i><span id="busuanzi_value_site_pv"></span><span></span></span></div></div></footer><i class="fa fa-arrow-up" id="go-up" aria-hidden="true"></i><script src="https://cdn.jsdelivr.net/npm/animejs@latest/anime.min.js"></script><script src="https://cdn.jsdelivr.net/npm/jquery@latest/dist/jquery.min.js"></script><script src="https://cdn.jsdelivr.net/npm/@fancyapps/fancybox@latest/dist/jquery.fancybox.min.js"></script><script src="https://cdn.jsdelivr.net/npm/velocity-animate@latest/velocity.min.js"></script><script src="https://cdn.jsdelivr.net/npm/velocity-ui-pack@latest/velocity.ui.min.js"></script><script src="/js/utils.js?version=1.9.0"></script><script src="/js/fancybox.js?version=1.9.0"></script><script src="/js/sidebar.js?version=1.9.0"></script><script src="/js/copy.js?version=1.9.0"></script><script src="/js/fireworks.js?version=1.9.0"></script><script src="/js/transition.js?version=1.9.0"></script><script src="/js/scroll.js?version=1.9.0"></script><script src="/js/head.js?version=1.9.0"></script><script>if(/Android|webOS|iPhone|iPod|iPad|BlackBerry/i.test(navigator.userAgent)) {
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